This invention relates to a conductive webs and fabrics, and more particularly to a laminate web wherein at least a central layer is conductive. In some embodiments the central layer comprises a plurality of spaced, parallel conductors.
Electrical cables are known in the art. Electrical cables can be used for power transmission or for signal transmission, and the technology for each is well developed. For example, design choices for performance parameters for power transmission cables, including conductor size and insulation requirements are well known. Likewise, design choices for performance parameters for signal transmission cables, such as signal speed, impedance, and shielding level, are equally well known.
For either power cables or signal transmission cables, two basic cable types are known: round and flat. Round cables are formed by the twisting, or xe2x80x9ccablingxe2x80x9d together of a plurality of individual insulated and/or shielded wires into an overall-jacketed cable having a generally round cross section. Flat cables are typically made by feeding a plurality of wires, each of which may be insulated and/or shielded (e.g., coaxial signal wires), into in a spaced apart, parallel arrangement, and held in such an arrangement by an overall jacket. Overall jackets for both round and flat cables are typically extruded on inline with the cable production.
In some cases, it is desirable to make a flat cable comprising flat conductors. In this type of cable, the conductors themselves have a flat, generally rectangular cross section. Such cables find use in such applications as board-to-board interconnections for electronic equipment, for example. The relatively low profile and greater flex life (for dynamic applications) make flat conductor flat cables ideal for these and many other applications. Examples of flat conductors cables include those manufactured and marketed by Axon Cable and Interconnect as Axojump(copyright) flat flexible cables.
One drawback to known methods of forming flat cables is production speed, particularly with small gauge conductors (e.g., below 36 AWG equivalent). For high quality cables it is required that each of the conductors feeding into the cable be held at a uniform tension, and spacing must be carefully maintained. As conductor size decreases (i.e., AWG increases), this requirement becomes more critical, and high production speeds are more difficult to achieve.
In addition to the problems of forming flat cables described above, for known methods of making flat cables comprising flat conductors, cost is a major factor. For many reasons, including technical complexity and relatively low usage, flat conductors are more expensive than round conductors, for equivalent gauge size.
Accordingly, it would be desirable to have a method of economically manufacturing flat cables for electrical power or signal transmission.
Additionally, it would desirable to have a method of economically manufacturing flat cables comprising flat conductors.
An electrical cable of the present invention comprises a plurality of spaced, parallel flat conductors. Each of the plurality of flat conductors was previously integral with each immediately adjacent flat conductor. A dielectric material holds the conductors in the spaced, parallel relationship. The dielectric material can be a polymer film, a nonwoven, or other polymer materials such as PTFE, or expanded PTFE.
The cable of the present invention is made by providing first and second webs of dielectric materials and a third sheet of conductive material. The first and second web materials are bonded to the third sheet of conductive material in a face-to-face layered relationship thereby forming a bonded laminate. The bonded laminate is then incrementally stretched to separate the sheet of conductive material in to spaced, parallel flat conductors.